It is well known that thermoplastic resin molded articles generally have poor abrasion resistance and are easily damaged with dust or by scratching, because of their soft surface. The minute surface scratches reduce the surface gloss, transparency, and smoothness, and deteriorate the appearance of the molded article. Such phenomena remarkably reduce the practical value of the molded article, especially the film of the thermoplastic resin, and the improvement of abrasion resistance of a thermoplastic resin molded article has long been desired.
Several means are proposed to improve the abrasion resistance of a thermoplastic resin molded article (for example, film, sheet, etc.). Examples of such means are, application of an inorganic coating layer to the surface, for example, by the vacuum deposition of inorganic glass, SiO.sub.2, metal oxides, etc., or by the coating of a condensate of a hydrolyzable silicon compound to the surface (as disclosed in the specifications of Japanese Patent Laid-open No. 52-25880, Japanese Patent Publication No. 53-39915, Japanese Patent Laid-open No. 53-97098, etc.), and application of an organic coating layer by coating the surface with a polyfunctional (meth)acrylate followed by curing the (meth)acrylate layer with electron rays, ultraviolet radiation or heat.
Although the inorganic coating layer gives a considerable abrasion resistance to the molded article, it has a drawback of cracking caused by stretching, compressing or bending because of its extremely low degree of elongation.
The application of the polyfunctional (meth)acrylate coating layer can be carried out, e.g. by the method disclosed in the specifications of Japanese Patent Laid-open Nos. 49-30466, 53-2567, and 53-102936, or by the use of a compound of the "NK-ester" series (Trade name of Shinnakamura Kagaku KK) known as a reactive crosslinking agent; however, the apparently incompatible requirements of high abrasion resistance and high elongation cannot be satisfied by the above methods because the high abrasion resistance inevitably results in the low elongation, and vice versa, in the above methods.
The isocyanurate ring-containing acrylate compounds disclosed in the Japanese Patent Laid-open No. 48-29880 are not yet satisfactory to give a laminate having sufficiently high abrasion resistance and elongation. The specification of the Japanese Patent Laid-open No. 49-125380 in which the method for the preparation of cyanurate ring-containing (meth)acrylates is disclosed, describes the film prepared by curing the cyanurate ring-containing (meth)acrylate thus obtained is either a "hard and rather brittle" film or a soft one.